Optical disk device, reproduction method of information on optical disk, and optical disk

Abstract

A digital RF signal resulting from A/D conversion of an RF signal reproduced from an optical disk is compared with a plurality of set values, so that a predetermined waveform is detected from the digital RF signal. The wavelength of the detected waveform is measured, and the A/D conversion is controlled based on this wavelength. Comparing the digital RF signal with the plural set values enables high-accuracy waveform detection.

1 . An optical disk device, comprising: 
 an A/D converter converting an RF signal reproduced from an optical disk from an analog value to a digital value to output a digital RF signal;    a waveform detecting unit comparing the outputted digital RF signal with a plurality of set values to detect a predetermined waveform from the digital RF signal;    a wavelength measuring unit measuring a wavelength of the detected waveform; and    a control signal generator generating a control signal controlling the A/D conversion in said A/D converter, based on the measured wavelength.    
   
   
       2 . The optical disk device as set forth in  claim 1 , wherein said waveform detecting unit detects the predetermined waveform based on whether the digital RF signal proximate to each of the plural set values presents an incremental change or a decremental change with time.  
   
   
       3 . The optical disk device as set forth in  claim 1 , wherein the predetermined wavelength is one of a combination of a peak and a valley and a combination of a valley and a peak.  
   
   
       4 . The optical disk device as set forth in  claim 3 , wherein said waveform detecting unit discriminates the combination of the peak and the valley and the combination of the valley and the peak from each other when detecting the waveform.  
   
   
       5 . The optical disk device as set forth in  claim 1 , wherein the number of the plural set values is three or more.  
   
   
       6 . The optical disk device as set forth in  claim 5 , wherein the plural set values are proximate to a slice level, larger than the slice level, and smaller than the slice level respectively.  
   
   
       7 . The optical disk device as set forth in  claim 1 , 
 wherein the detected predetermined waveform includes a plurality of wavelengths, and    the optical disk device, further comprising:    a wavelength selecting unit selecting the detected waveform based on a ratio of the measured plural wavelengths.    
   
   
       8 . The optical disk device as set forth in  claim 7 , further comprising: 
 a longest value holding unit holding a longest value of the wavelengths in the selected waveform; and    a longest expected value holding unit holding a longest wavelength expected value,    wherein said control signal generator further comprises a frequency error calculating unit which compares the held longest value of the wavelengths and the held longest wavelength expected value to calculate an error of a cycle of the A/D conversion in said A/D converter.    
   
   
       9 . The optical disk device as set forth in  claim 8 , wherein said longest value holding unit holds the longest value of the measured wavelengths that falls within a predetermined range.  
   
   
       10 . A reproduction method of information on an optical disk, comprising: 
 converting by an A/D converter an RF signal reproduced from an optical disk from an analog value to a digital value to output a digital RF signal;    comparing the outputted digital RF signal with a plurality of set values to detect a predetermined waveform from the digital RF signal;    measuring a wavelength of the detected waveform; and    generating a control signal controlling the A/D conversion in the AD converter, based on the measured wavelength.    
   
   
       11 . The reproduction method of information on the optical disk as set forth in  claim 10 , 
 wherein said waveform detection includes detecting the predetermined waveform based on whether the digital RF signal proximate to each of the plural set values presents an incremental change or a decremental change with time.    
   
   
       12 . The reproduction method of information on the optical disk device as set forth in  claim 10 , wherein the predetermined waveform is one of a combination of a peak and a valley and a combination of a valley and a peak.  
   
   
       13 . The reproduction method of information on the optical disk as set forth in  claim 12 , wherein said waveform detection includes discriminating the combination of the peak and the valley and the combination of the valley and the peak from each other to detect the waveform.  
   
   
       14 . The reproduction method of information on the optical disk as set forth in  claim 10 , wherein the number of the plural set values is three or more.  
   
   
       15 . The reproduction method of information on the optical disk as set forth in  claim 14 , wherein the plural set values are proximate to a slice level, larger than the slice level, and smaller than the slice level, respectively.  
   
   
       16 . The reproduction method of information on the optical disk as set forth in  claim 10 , wherein the detected predetermined waveform includes a plurality of wavelengths, and 
 the reproduction method further comprising    selecting the detected waveform based on a ratio of the measured plural wavelengths.    
   
   
       17 . The reproduction method of information on the optical disk as set forth in  claim 16 , further comprising 
 holding a longest value of the wavelengths in the selected waveform,    wherein said generation of the control signal further comprises comparing the held longest value of the wavelengths and a longest wavelength expected value held by a longest expected value holding unit to calculate an error of a cycle of the A/D conversion in the A/D converter.    
   
   
       18 . The reproduction method of information on the optical disk as set forth in  claim 17 , wherein said holding the longest value of the wavelengths in the selected waveform comprises holding a longest value of the measured wavelengths that falls within a predetermined range.  
   
   
       19 . An optical disk whose information reproduced by a reproduction method, the reproduction method comprising: 
 converting by an A/D converter an RF signal reproduced from an optical disk from an analog value to a digital value to output a digital RF signal;    comparing the outputted digital RF signal with a plurality of set values to detect a predetermined waveform from the digital RF signal;    measuring a wavelength of the detected waveform; and    generating a control signal controlling the A/D conversion in the AD converter, based on the measured wavelength.